Vacuum hubs failed (sorry!) any ideas/worth effort

So! 1998 Jimny, vacuum system apparently worked until a couple of months ago but I suspect the front hubs were just locked on and corrosion had blocked the pipes so the system thought it was working correctly, though 4wd definitely did work. 

Anyway it packed in.  I had a look and all of the metal pipes are gone in places, some of the silicone ones had holes in. Replaced entire pipe runs from the solenoids to the hubs with silicone, red for lock blue for unlock to make it easier to keep track.

Everything but the passenger hub is working. So it won’t go into 4wd whilst  the passenger hub connected to the vacuum lines, but if I plug the lines at the hub so it’s just the right hand side, it’ll go in and out just fine. Blowing through the hub there is a bit of resistance but evidently a leak.

Recently done the king pin bearings and just this morning did the wheel bearing thinking it might be this, as it was showing wear and had no grease in. admittedly I didn’t torque the bearing to spec this morning as I didn’t have the right wrench, just did it with a massive breaker and feel.

wondering if anyone has any incline what it could be leaking within the hub assembly itself and ultimately… is it even worth chasing down or do I just get manual hubs?

oh and the left hand hub/bellows was full of rust and crap, I’ve dismantled it and cleaned it. No difference, swapped them over and it’s the same symptoms so the issue seems to be something not sealing within the spindle/bearing side, or even a minor crack?

as always greatly appreciate any input!